On the basis of the primitive dyadic time relation “earlier than” we develop subsequently temporal relations and orders of things in mereological terms. The basic mereological relation is the relation of part to whole, which permits the whole as part of itself. Starting point of the mereo-chronological systematization is Alfred Tarski’s development of the characteristics of the relations of part and time and their correlations in the appendix E of Henry Woodger’s application of mathematical and logical methods in biology in (...) “The Axiomatic Method in Biology” (1937). Tarski’s reasoning is modified and expanded in different ways. Modifications are made with respect to the following three items: the choice of the postulated axioms and cited theorems, the transscription of the axioms and theorems formalized by Tarski in Principia Mathematica-notation in symbolism of modern First-Order Predicate Logic and the detailed proofs of the theorems. The intended meaning of the axioms and theorems is given in common everyday language and − if possible − illustrating diagrams are added. -/- Things in time and momentary things are introduced (§ 2) and their relations to things in general are contemplated (§ 3.1). By means of the relation of temporal coincidence certain relations between momentary things are dealt with (§ 3.2). For momentary things another time relation “wholly earlier” is defined (§ 3.3), which leads together with the definition of momentary worlds to a corresponding relation between them (§ 3.4). This relation eventually gives us a temporal order of momentary worlds, which is isomorphic to the continuum of real numbers (§ 3.4). Momentary phases as “slices” of single things (§ 3.5), the fundamental concept of an organized (biological) unity and the relation “wholly earlier” between momentary phases of an organized unity have the result that the duration of life of an organized unity can be modelled as a closed interval in the sequence of momentary worlds (§ 4). Finally by means of a dyadic time relation “wholly earlier” between things introduced by Tarski in the appendix E the time relations of copresence, of temporal part, of simultaneousness and of genuine temporal part are defined (§ 5). (shrink)